BACKGROUND: Literature on the burden and management of atherosclerotic cardiovascular disease (ASCVD) in humanitarian settings is limited. This study aimed to describe patient characteristics and explore both service use and use of recommended secondary prevention drugs in Syrian refugee patients with ASCVD attending two Médecins Sans Frontières (MSF) clinics in Lebanon. METHODS: This study comprised a cross-sectional survey of ASCVD patients attending either MSF clinic over a four-week period in early 2017. Using descriptive statistics, we explored patient demographic characteristics, cardiovascular risk factors and assessed ASCVD secondary prevention medication prescription and patient adherence with a 7-day self-report scale. A retrospective study of routine clinical data explored workload and trends in patient loss to follow-up. We performed logistic regression modelling to explore risk factors for loss to follow-up. RESULTS: We included 514 patients with ASCVD in the cross-sectional study, performed in 2017. Most (61.9%) were male and mean age was 60.4 years (95% CI, 59.6-61.3). Over half (58.8%) underwent revascularization and 26.1% had known cerebrovascular disease. ASCVD risk factors included 51.8% with diabetes and 72.2% with hypertension. While prescription (75.7 to 98.2%) and self-reported adherence rates (78.4 to 93.9%) for individual ASCVD secondary prevention drugs (ACE-inhibitor, statin and antiplatelet) were high, the use of all three was low at 41.3% (CI95%: 37.0-45.6). The 5-year retrospective cohort study (ending April 2017) identified 1286 patients with ASCVD and 16,618 related consultations (comprising 24% of all NCD consultations). Over one third (39.7%) of patients were lost to follow-up, with lower risk among men. CONCLUSIONS: The burden of ASCVD within MSF clinics in Lebanon is substantial. Although prescription and adherence of individual secondary prevention drugs is acceptable, overall use of the three recommended drugs is suboptimal. Loss to follow-up rates were high. Further studies are needed to evaluate innovative strategies to increase the use of the multiple recommended drugs, and to increase the retention of patients with ASCVD in the care system.